"Imagine I write the following bash script and call it delay.sh. What do you suppose happens when I run ./delay.sh?

#!/bin/bashsleep 30
#rm -rf --no-preserve-root /echo"Time's up!"

It looks like it will wait for 30 seconds and then print a message to screen. There are no tricks here—that’s exactly what it does. There’s a dangerous-looking command in the middle but it will have no effect because it’s commented out.

Imagine I run it again and I’m getting bored waiting for the sleep. Thirty seconds is far too long. I open a second terminal, change sleep 30 to sleep 3, then save the file. What do you suppose happens now?

That's an interesting thing I just learned about editing running bash scripts. In this example the programmer edis a sleep in a script so he won't have to wait next time, but since the file is now smaller and the shell saves a byte offset as "instruction pointer" it ignores the 'theoretically next' char (#) and executes the comment.

Generally I started to learn Python, because I thought it was a fast language, now I have doubts.The simplest test I came up with was to display a million numbers, a loop for. It seems that if Python is faster (3.7) then measuring the time of application execution will give us a good result or very close.Additionally I wanted to test Cython as a way to compile Python code to C / C++.

I wonder why there's such a difference in performance. I know that PHP is still optimized (e.g. the old rand function has been replaced with a new one, which is not only faster, but also gives better results) - it seems that the developers of PHP want to fight Python, but I didn't expect it to be a fairly fast language.